Inclosed-arc device and method of operating the same.



G. M. J. MACKAY.

INCLOSED ARC DEVICE AND METHOD OF OPERATING THE SAME.

APPLICATION FILED OCT- 30,1915- ]Patented Dec. 12, W16.

inventor fiewrgge m.J.mackag,

GEORGE M. J. MACKAY, 0F SCHENECTADY, NEW

"roan, ASSIGNOB '10 eminent ELECTRIC COMPANY, A CORPORATION 01E NEW YORK.

ENCLOSED-ARC DEVICE AND METHOD OF OPERATING THE Specification of Letters Patent.

SAME.

liatented Dec. 1123, 119ml.

Application filed october 30, 1915. serial No. anti-)7.

To all whom it may concern:

Be it known that I, Gnonon M. J. MAGKAY, a subject ofthe King of-Great Britaim'residing at Schenectady, county of Schenectady, State of New York, have invented certain new and useful Improvements in Tnclosed-Arc Devices and ing the Same, specification.

The present invention relates to incl'osed are devices having a cathode consisting of highly refractory material operating at incandescence in a gaseous atmosphere.

T have discovered that a markedly lowered voltage drop or loss in the arc is secured in a device of this type containing gases protecting the electrodes from chemical deterioration and electrical disintegration when there is provided Within the device a material as, for example, calcium and related alkaline-earth metals, magnesium, or non-metallic absorbents, such as phosphorous pentoxid, which, while having no atfinity for the gaseous filling, is chemically active with respect to impurities in the gaseous filling, to produce compounds of negligibly low vapor pressure ,with the gaseous impurities. In the case of a filling of argon, the most deleterious of the gaseous impurities tending to increase the drop of potential in the arc appear to be water vapor, hydrogen and nitrogen.

y improvement will be more fully understood and appreciated by reference to the following description of several specific embodiments of my invention.

Tn connection with this description, I have shown diagrammatically in the accompanying drawing in Figure 1 by way of example, a device containing an incandescent cathode, upon which the material to be vaporized is applied and in Fig. 2 a device provided with a capsule containing the material to be vaporized. Fig. 3 shows a detail of a modification.

The device comprises an envelop 1. con sisting of glass, such as low expansion or sodium-magnesium bo-ro-silicate glass. The

of which the following is a cathode 2 consists of highly refractory material having a melting point exceeding at least about 2000 (3., such for example, as

tungsten, tantalum, carbon or the like. The.

anode 3 consists of conductive material, for example, tungsten, carbon or other solids, but in some cases, a liquid such as mercury Methods of 0perat may be used, as indicated by anode 3 in Fig. 3. The cathode current-supply wires 4, 5 and the anode conductor 6 are sealed respectively ,into the stems 7, 8 in the usual manner.

The globe is first evacuated and then filled with a suitable gas at considerable pressure. Removal of water vapor from the bulb by heating the bulb during evacuation is desirable but not so necessary as when no chemical addition is used in accordance with my lnvention. Various gases may be used depending on the character of the service required of the device. The monatomic gases of the argon group, also nitrogen, and carbon monoxid, have been used.

The gaseous pressure also will vary with the nature of the device. I may say that it should be above a pressure of several millimeters of mercury and will moreusually approach atmospheric pressure in order of magnitude. In a device used for rectifying alternating current at low voltages, argon at a pressure of about 5 to 12 c. m. of mercury is found suitable.

The material chemically active with respect to deleterious gaseous impurities in the gas filling, or deleterious gases contained in the electrodes and the glass, may be vaporized by the cathode when heated to incandescence by passage of current, or may be simply placed in the globe in any convenient manner. Metalliccalciumor magnesium may, for example, be introduced as a small strip of foil or Wire 9 placed upon or wrapped about one of the cathode conductors and in proximity to the cathode so as to be vaporized by the heat of the are or by the incandescent cathode. As shown in Fig. 2, the chemical addition may be placed in a small glass capsule 10 located in an open-ended tube 11. The tip of the capsule may be broken by shaking after the evacuation of the container is complete.

In devices containing a filling of nitrogen, phosphorous pentoxid is preferred for cleaning up water vaporand other gaseous impurities. In devices filled with a monatomic gas, such as argon, neon, krypton, xenon, or helium, I prefer to use calcium, magnesium or one of the related metals. Calcium vapor will absorb all gases except the very inert monatomic gases although phosphorous pentoxid maybe also used with good results for purifying monatomic gases in situ. Solid phosphorous pentoxid, P 0 in an argon-filled device will remove hydrogen, water vapor and apparently also nitrogen to some extent. Some of the pentoxid is reduced by the hydrogen, forming water vapor which is in turn absorbed by the remaining pentoxid to form a gummy phosphoric acid of very low vapor pressure.

The beneficial effect of the purifying agents used in accordance with my invention should not be confused with the chemical purification of the gases prior to their introduction into the envelop. 'lhe chemical agent placed in contact with the atmosphere within the arc device in addition to purifying the gas filling at the beginning of the operation of the device, acts continuously to remove traces of deleterious gas given off during its operation from the electrodes, and the glass envelop. Apparently the arc activates the gaseous impurities so that they combine more readily with the chemical agents within the bulb.

By the use of agas-absorbing chemical agent in accordance with my invention, the potential drop, or loss in an incandescent cathode device is reduced to one-half, and in many cases even to less than one-half of the drop heretofore occurring in devices filled with the above mentioned gases purified most carefully only by known chemical methods upon their introduction into the device, thereby making in some cases a device efficient enough to be usable for commercial uses from which it would otherwise be excluded.

To give specific illustrations, I may state that an incandescent cathode device carrying about six amperes when filled with argon purified. by ordinary methods has an arc drop of about 30 to 40 volts. When the envelop contains a small quantity of phosphorous pentoxid, as above described, the arc drop is reduced to about ten volts. Similarly a six ampere neon tube containing, at a pressure of about half an atmosphere, neon gas purified by the usual methods has an arc drop of about 50 volts. The same tube when provided with metallic calcium acting to purify the gas in situ in the manner above described has anarc drop of about20 volts.

What I claim as new and desire to secure by Letters Patent of the United States, is

1. The combination of a sealed envelop, arcing electrodes therein, one of which is adapted to operate at incandescence, an atmosphere of gas chemically inert with respect to said electrodes and a material chemically active with respect to impurities in said gas acting to continuously combine with gaseous impurities evolved from the electrodes and walls of the envelop during the operation of an arc between said electrodes.

2. The combination of a sealed-envelop, a cathode of refractory material adapted to operate at incandesccnce, a cooperating anode, a filling of gas inert chemically with respect to said electrodes and suppressing the electrical disintegration of the cathode and a material forming compounds of negligibly low vapor pressure with gaseous impurities tending to increase the fall of potential in the arc between said electrodes.

3. An arc device comprising the combination of a sealed envelop, a cathode of material having a melting point exceeding about 2000 0., a coiipe 'ating anode, a filling of monatomic gas having at the operating temperature of the device a pressure of at least several millimeters of mercury, and a material forming under the operating conditions of the device compounds of negligibly low vapor pressure with polyatomic impurities in said gas.

4. An arc device comprising the combination of a sealed envelop, a tungsten cathode, an anode, a filling of argon at a pressure materially greater than one millimeter of mercury pressure and a quantity of material chemically active with respect to water vapor.

5. Themethod of purifying the gaseous atmosphere surrounding an incandescent cathode and a cooperating anode in a closed envelop which consists in liberating during the operation of the arc in contact with said atmosphere a vapor having no afiinity for said gaseous atmosphere but chemically active with respect to deleterious gaseous impurities given off by the envelop and said electrodes.

6. The method of lowering the voltage drop of an arc between an incandescent cathode and an anode in an atmosphere of argon which consists in vaporizing during the operation of the arc in contact with the argon a material combining with water vapor to form solid materials of low vapor pressure.

In witness whereof, I have hereunto set my hand this 29th day of October, 1915.

GEORGE M. J. MACKAY. 

